KR101867612B1 - Apparatus and method for transmitting and receiving data - Google Patents

Abstract

A data transmitting apparatus generates a plurality of pilot signals to be used for channel estimation in a data receiving apparatus, generates a plurality of data symbols and a plurality of pilot symbols by symbol-mapping a plurality of input data signals and a plurality of pilot signals, And converts the input symbols in the frequency domain including the symbols and the plurality of pilot symbols from the frequency domain to the real signals in the time domain and then modulates the input symbols. The data transmitting apparatus controls the magnitude of the sine signal for each modulated real signal with a variable gain according to the control signal, and then transmits the signal.

Description

[0001] APPARATUS AND METHOD FOR TRANSMITTING AND RECEIVING DATA [0002]

The present invention relates to an apparatus and method for transmitting and receiving data, and more particularly, to a system and method for transmitting and receiving data by using an OFDM (Orthogonal Frequency Division Multiplexing) (PAPR) for controlling data transmission and reception.

OFDM can be implemented by a simple equalizer and is also robust to multipath fading and can be used for a wireless local area network (WLAN), a wireless metropolitan area network (WMAN) ), Digital audio broadcasting (DAB), digital video broadcasting (DVB), and the like.

However, since OFDM uses multiple carriers, the signals on the same phase are summed up to generate a high peak-to-average power ratio (PAPR) of up to 12 dB, and the power PAPR of the OFDM transmitter the operating point of the amplifier is located in the non-linear region and non-linear distortion of the signal occurs. Therefore, in the OFDM system, the power amplifier is back off to reduce the influence of the PAPR. If the power amplifier is not provided with a sufficient backoff, the frequency spectrum of the system is widened and distortion due to inter- Resulting in deterioration of system performance. Therefore, it is essential to lower the PAPR for power efficiency and miniaturization of the OFDM transmitter.

Combining a phase modulation (PM) or a frequency modulation (FM) scheme with an OFDM scheme having a high PAPR of up to 12dB can reduce the PAPR to 0dB.

The combination of the PM system and the FM system, which are analog systems in the OFDM system, deteriorates the reception performance in the channel in which the multipath exists. The FM system has a disadvantage that the required frequency band is wide and the degree of degradation of the reception performance is more serious than the PM system .

In the case of Visible Light Communication (VLC) using OFDM, it is effective to reduce the PAPR to 0 dB. However, in the case of optical communication other than infrared light, it is necessary to increase the PAPR for the reception performance. Therefore, the uniform PAPR control degrades the performance of the system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a data transmission and reception apparatus and method capable of lowering PAPR in a system for transmitting data using an OFDM scheme and ensuring stable reception performance in a multi-path channel.

According to one embodiment of the present invention, an apparatus for transmitting data is provided. The data transmitting apparatus includes a pilot generating unit, a symbol mapping unit, a real signal converting unit, each modulating unit, a PAPR control and power normalizing unit, and a signal transmitting unit. The pilot generating section generates at least one pilot signal to be used for channel estimation in the data receiving apparatus. The symbol mapping unit generates a plurality of data symbols and at least one pilot symbol by symbol-mapping the plurality of data signals and the at least one pilot signal. The real signal converter converts an input symbol in a frequency domain including the plurality of data symbols and the at least one pilot symbol into a real signal in a time domain. Each modulating unit modulates the real signal. The PAPR control and power normalization unit adjusts the magnitude of the sine component of each modulated real signal according to the first gain and varies the first gain according to the input signal. The signal transmitter converts the resized real signal into a radio frequency signal and transmits the radio frequency signal.

Wherein the data transmitting apparatus further comprises a symbol arranging unit that sets a pilot symbol corresponding to each of the plurality of data symbol groups each including at least one data symbol, Two symbols are generated using the pilot symbols, and the two symbols are arranged in the respective data symbol groups and output to the real signal converter.

The symbol arranger may generate one symbol of the two symbols by adding the one data symbol and the pilot symbol and subtract the one data symbol and the pilot symbol to generate another symbol of the two symbols have.

Each modulator may include a phase controller for controlling the magnitude of the real signal according to a second gain, and a modulator for modulating the real signal with a cosine signal and a sine signal.

Wherein the real signal conversion unit comprises: a normalization unit for normalizing the input symbol so that the average power of the input symbol is 1; an inverse fast Fourier transform unit for inverse fast Fourier transforming a plurality of input signals; And an input signal processor for inputting the conjugate complex symbol obtained by the conjugate complex conversion to the inverse fast Fourier transformer.

Wherein the PAPR control and power normalization unit comprises: a PAPR controller for controlling a magnitude of a sine component of each modulated real signal according to the first gain; a PAPR controller for multiplying a cosine component of the real signal by a set value for normalization, And a second multiplier for multiplying a sine component of the real signal whose magnitude is controlled according to the first gain by the set value to generate a baseband Q signal, wherein the first multiplier has a gain of 1 The PAPR may be zero.

According to another embodiment of the present invention, an apparatus for receiving data is provided. The data receiving apparatus includes a power compensating unit, a weightsection, a normalization and real signal inverse transforming unit, a pilot extracting unit, a channel estimating unit, a channel equalizing unit, and a symbol demapping unit. The power compensating unit compensates the size of the baseband signal corresponding to the received data in accordance with the size adjusted by the data transmitting apparatus for PAPR control. Each demodulator demodulates the size-compensated baseband signal. The normalization and real signal inverse transformer transforms each demodulated signal into a plurality of parallel symbols in the frequency domain in a time domain through fast Fourier transform. The pilot extracting unit extracts pilot symbols and data symbols from the parallel symbols. The channel estimator estimates a channel using the pilot symbol. The channel equalizer compensates the channel using the estimated channel. The symbol demapping unit symbol demaps the data symbols to generate a plurality of data signals to recover the data.

The demodulator may include a phase estimator for calculating a phase estimate value of the baseband signal, and a phase compensator for compensating a phase of the baseband signal from the phase estimate.

The phase estimator may calculate an average value of the phase of the baseband signal and calculate the phase estimate value using an inverse tangent of the average value.

The phase estimator may calculate the phase estimation value using the inverse tangent after filtering the baseband signal.

The pilot extracting unit may obtain positional information of two symbols generated by using the pilot symbols in the data transmitting apparatus from the parallel symbols, and may extract pilot symbols and data symbols using the two symbols corresponding to the positional information .

The power compensation unit includes two multipliers for compensating the magnitudes of the I signal and the Q signal of the baseband signal, and a PAPR controller for dividing the magnitude-compensated Q signal into gains, have.

Wherein the real signal inverse transformer comprises a fast Fourier transformer for performing fast Fourier transform on a plurality of input signals to generate the parallel symbols, a serial-to-parallel converter for converting the demodulated baseband signals from a serial signal to a parallel signal, And a signal processing unit for outputting a part of the parallel symbols to the demapping unit.

According to another embodiment of the present invention, a method is provided for a data transmitting apparatus to transmit data. A data transmitting method includes generating a plurality of pilot signals to be used for channel estimation in a data receiving apparatus, generating a plurality of data symbols and a plurality of pilot symbols by symbol-mapping a plurality of input signals and the plurality of pilot signals, Converting a frequency domain input symbol including the plurality of data symbols and the plurality of pilot symbols from a frequency domain to a real signal in a time domain, modulating each of the real signals, modulating each modulated real signal And converting the modulated real signal into a radio frequency signal and transmitting the radio frequency signal.

Wherein the generating comprises: setting a pilot symbol corresponding to each of a plurality of data symbol groups each including at least one data symbol, generating two symbols using a data symbol and a pilot symbol of each data symbol group, And arranging the two symbols in the respective data symbol groups.

The controlling step may include varying the gain according to an input control signal.

According to another embodiment of the present invention, a method is provided for a data receiving apparatus to receive data. The data receiving method includes: compensating a magnitude of a baseband signal corresponding to received data; demodulating the baseband signal; demodulating each demodulated signal by a fast Fourier transform to generate a plurality of parallel symbols Extracting pilot symbols and data symbols from the parallel symbols, compensating a channel estimated using the pilot symbols, and recovering the received data by symbol demapping the data symbols. .

Each of the demodulating steps may include estimating a phase of the baseband signal, and compensating a phase of the baseband signal using a phase estimation value.

The extracting step includes obtaining position information of two symbols generated by using a pilot symbol in the data transmitting apparatus, and extracting pilot symbols and data symbols using two symbols corresponding to the position information can do.

According to the embodiment of the present invention, by modulating and transmitting data by a method combining a PM scheme with an OFDM scheme, PAPR can be lowered to 0 dB, and PAPR can be varied according to a reception environment, thereby improving reception performance. Therefore, it is possible to provide a service considering both PAPR and reception performance without changing the specification of the transmitter in the multipath channel. For example, in the case of visible light wireless communication using illumination, the occurrence of flicker can be prevented by controlling the PAPR to 0 dB, and in the case of communication using wireless light other than infrared light, the reception performance can be improved by raising the PAPR.

1 is a block diagram illustrating an OFDM transmission apparatus according to an embodiment of the present invention.
2 is a flowchart illustrating a signal transmission method of an OFDM transmission apparatus according to an embodiment of the present invention.
3 is a diagram showing an example of the pilot generator shown in FIG.
4 is a diagram showing an example of a method of generating a pilot signal.
5 is a diagram illustrating an example of a symbol mapped by the symbol mapping unit of FIG.
6 is a diagram illustrating an example of a symbol normalized by the symbol mapping unit of FIG.
7 is a diagram illustrating an example of a data symbol grouping method performed by the pilot arrangement unit shown in FIG.
8 is a diagram illustrating an example of a method of arranging data symbols and pilot symbols performed by the pilot arranging unit shown in FIG.
FIG. 9 is a diagram showing the real signal conversion unit shown in FIG. 1. FIG.
FIG. 10 is a diagram showing each modulating unit shown in FIG. 1. FIG.
11 is a diagram showing the phase size distribution of the input signal of each modulation section.
12 is a diagram showing a phase size distribution for the output signal of each modulation section.
13 is a view showing the PCPN shown in Fig.
14 is a diagram illustrating an OFDM receiving apparatus according to an embodiment of the present invention.
15 is a flowchart illustrating a data receiving method of an OFDM receiving apparatus according to an embodiment of the present invention.
16 is a diagram showing an example of a received signal processing unit shown in FIG.
17 is a diagram showing the power compensation unit shown in Fig.
FIG. 18 is a diagram showing each demodulating unit shown in FIG. 10; FIG.
Figs. 19 and 20 are diagrams showing the phase estimator shown in Fig. 18, respectively.
FIG. 21 is a diagram showing the phase compensation unit shown in FIG. 18;
22 is a diagram showing the real signal converter shown in Fig.
23 is a diagram showing a pilot extraction method of the pilot extraction unit shown in FIG.
FIG. 24 is a diagram illustrating a channel estimator shown in FIG. 14. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification and claims, when a section is referred to as " including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Now, an apparatus and method for transmitting / receiving data according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram illustrating an OFDM transmitting apparatus according to an embodiment of the present invention, and FIG. 2 is a flowchart illustrating a signal transmitting method of an OFDM transmitting apparatus according to an embodiment of the present invention.

1, the OFDM transmitter 100 includes a serial-to-parallel converter (SPC) 110, a pilot generator 120, a symbol mapper 130, A Real Signal Converter 150, an Angle Modulation Unit 160, a Peak to Average Power Ratio (PAPR) control and a PAPR Control & Power Normalize unit (PCPN) 170, and a signal transmitter 180.

Referring to FIG. 2, when a plurality of serial data signals corresponding to bit-type input data are inputted, the SPC 110 converts a plurality of serial data signals into a plurality of parallel data signals (S201).

The pilot generating unit 120 generates at least one pilot signal to be used for channel estimation and channel equalization in the OFDM receiving apparatus (S203).

The symbol mapping unit 130 performs symbol mapping through digital modulation such as Binary Phase Shift Keying (BPSK), Quadrature Amplitude Modulation (QAM), 16-QAM, and 64-QAM on a plurality of parallel data signals and at least one pilot signal. Thereby generating a plurality of data symbols and at least one pilot symbol (S205).

The pilot arrangement unit 140 arranges at least one pilot symbol and a plurality of data symbols so as to facilitate channel estimation (S207).

The real signal converter 150 performs an inverse fast Fourier transform (IFFT) on at least one pilot symbol and a plurality of data symbols to convert the frequency domain into a real signal in a time domain (S209). The NRSC 130 converts the real signal of the time domain into a serial signal (S211).

Each modulator 160 modulates the real signal to adjust the magnitude of the real signal (S213). A phase modulation (PM) scheme can be used for each modulation scheme.

The PCPN 170 adjusts the magnitude of the sine component of each modulated real signal according to the gain Gain to control the PAPR (S215), and performs power normalization (S217).

Next, the signal transmitter 180 multiplies the real component of the power normalized signal by A, multiplies the imaginary component of the power normalized signal by B, adds the two components, and converts the power normalized signal into a radio frequency signal (S219) . Here, A may be a cos (2πf _c t) or sin (2πf _c t), B is a can be a cos (2πf _c t) or sin (2πf _c t), A is different from the other may be a value. f _c is radio frequency. In FIG. 1, A is represented by cos (2? F _c t) and B is represented by sin (2? F _c t). Or the signal transmitter 180 may multiply the imaginary component of the power normalized signal by -B.

The signal transmitting unit 160 transmits a radio frequency signal (S221). The radio frequency signal transmitted from the OFDM transmission apparatus 100 can be defined as an OFDM signal.

Then, the OFDM transmission apparatus 100 will be described in detail with reference to FIG. 3 to FIG.

FIG. 3 is a diagram illustrating an example of the pilot generator shown in FIG. 1, and FIG. 4 is a diagram illustrating an example of a pilot signal generation method.

The pilot generating unit 120 may use a pseudo random noise (PN) code that can reproduce while showing a noise characteristic similar to a random sequence, to generate a pilot signal. 3, the pilot generating unit 120 may include a PN code generator 121 composed of shift registers 1211, 1213, and 1215 and a computing unit 1217, and a bit processing unit 123 have. Alternatively, the pilot generator 120 may use the PN code generated from the PN code generator to generate a pilot signal.

The shift registers 1211, 1213 and 1215 shift the input signal. The operator 127 performs an exclusive OR (XOR) operation on the two input signals. That is, the operator 127 outputs 0 when the two input signals have the same bit, and outputs 1 when the two input signals have different bits.

The bit processing unit 123 selects the pilot signal from the PN code.

For example, assuming that the initial values R1, R2 and R3 of the shift registers 121, 123 and 125 are (1, 1, 1), the repetition period is 7 (= 2 ^m -1) The PN code output from the code generator 121 is "1 1 1 0 1 0 0". Here, m is the number of shift registers. If the number of pilot signals is 5, 5 bits or " 1 1 1 0 1 " are selected from the 7-bit PN code " 1 1 1 0 1 0 0 ", and " 1 1 1 0 1 " Setting.

The bit processing unit 123 may generate a plurality of PN codes for base station identification by shifting (phase offset) the PN code by 1 bit for base station identification. For example, when the PN code is " 1 1 1 0 1 0 0 ", seven PN codes can be generated as shown in FIG. 4, and each of the bits corresponding to the number of pilots in each PN code is selected, Signal.

FIG. 5 is a diagram illustrating an example of a symbol mapped by the symbol mapping unit of FIG. 1, and FIG. 6 is a diagram illustrating an example of a symbol normalized by the symbol mapping unit of FIG.

The symbol mapping unit 130 maps a plurality of parallel data signals and at least one pilot signal to data symbols and pilot symbols representing positions in a constellation according to a modulation scheme such as BPSK, QAM, 16-QAM, 64-QAM, And the mapped data symbols and pilot symbols may be as shown in FIG. That is, the mapped symbols are complex signals.

)이 되고, 입력 심볼에

을 곱함으로써 입력 심볼을 정규화할 수 있으며, 정규화된 심볼은 도 6과 같이 나타날 수 있다. The symbol mapping unit 130 normalizes the data symbols and the pilot symbols. In order to normalize the data symbols and the pilot symbols, the symbol mapping unit 130 obtains an average value by taking an absolute value of an input symbol, performing a square calculation on the input symbol, obtaining a square root of the obtained average value, and dividing the input symbol by a square root, 1 < / RTI > For example, when the symbols mapped by the symbol mapping unit 130 are as shown in FIG. 5, the average value is 10 (=

), And the input symbol

, And the normalized symbols may appear as shown in FIG.

FIG. 7 is a diagram illustrating an example of a method of grouping data symbols performed by the pilot arrangement unit shown in FIG. 1, FIG. 8 is a flowchart illustrating a method of arranging data symbols and pilot symbols performed by the pilot arrangement unit shown in FIG. Fig.

The pilot symbols are used for channel equalization of the data symbols, and the pilot arrangement unit 240 determines the group of data symbols to be channelized using each pilot symbol. The number of data symbol groups corresponds to the number of file symbols.

In the case where the number of pilot symbols is five, the pilot arrangement unit 140 groups the plurality of data symbols into five data symbol groups. For example, as shown in FIG. 7, the pilot arrangement unit 140 may select the first three data symbols as a group of data symbols to be channelized using the first pilot symbol, and use the second pilot symbol The next seven data symbols can be selected as the data symbol group to be channel equalized. The pilot allocation unit 140 may select the last 15 data symbols as a data symbol group to be channelized using the fifth pilot symbol.

Next, the pilot arrangement unit 140 selects one data symbol in each data symbol group, adds and subtracts the pilot symbol and the selected data symbol corresponding to each data symbol group, and generates two new data symbols. For example, if the pilot symbol is 1 and the selected data symbol is 3 + j * 5, the data symbol plus 4 + j * 5 is added to the pilot symbol and the data symbol minus the pilot symbol is -2-j * 5 . Alternatively, a pilot symbol may be added to or subtracted from the selected data symbol. In this case, the data symbol to which the pilot symbol is added is 4 + j * 5, and the data symbol minus the pilot symbol is 2 + j * 5.

로 나누고, 각 그룹의 임의의 위치에 생성된 두 데이터 심볼을 배치한다. 예를 들어, 파일럿 배치부(240)는 도 8과 같이 새로운 두 데이터 심볼을 임의의 위치에 배치할 수 있다. 이렇게 하면, 각 데이터 심볼 그룹은 데이터 심볼의 수가 1개씩 증가된다. Thus, when two new data symbols are generated, the pilot arrangement unit 140 allocates two new data symbols for normalization

And arranges two generated data symbols at arbitrary positions in each group. For example, the pilot arrangement unit 240 can arrange two new data symbols at arbitrary positions as shown in FIG. In this way, the number of data symbols in each data symbol group is incremented by one.

FIG. 9 is a diagram showing the real signal conversion unit shown in FIG. 1. FIG.

9, the real signal converter 150 includes an input signal processor 151, an IFFT unit 153, a parallel-to-serial converter (PSC) 155, and a multiplier 157 do.

The input signal processing unit 151 converts the input data symbols and the pilot symbols into the input signals X (0) and X (0) of the IFFT unit 153 to convert the input data symbols and the pilot symbols from the frequency domain into the real- X (1), ... , X (N-1), X (N), X (N + 1), ... , X (2N-1)]. Here, N (exponentiation power of 2) represents the number of symbols, and if the number of symbols is N, the size of the IFFT can be 2N.

That is, the input signal processing unit 151 receives the input signals [X (0), X (1), ...) of the IFFT unit 153 , X (N-1), X (N), X (N + 1), ... (N), X (N + 1), ...) of the IFFT unit 153 using N data symbols, , X (2N-1)], and uses the N data symbols by conjugate complex conjugation. The 0th data symbol is 0 and therefore the data symbol input to the input signals X (0), X (N) is 0. That is, the input signals X (1), ..., X (N- 1) and the data symbols of the input signal X (2N-k) are subjected to the conjugate complex conversion on the input signals X (N + 1), ..., X Where k is N + 1, N + 2, ..., 2N-1.

(X (1), ..., X (N-1), X (N), X (N + 1), ..., X (2N-1)] to the IFFT unit 153, ..., X (2N), X (N), X (N), X (N) (0), X '(1), ..., X' (N-1)) in the frequency domain in the frequency domain by using the data symbols and the pilot symbols, that is, the input symbols, ), X '(N), X' (N + 1), ..., X '(2N-1).

PSC 155 converts the real-time signal in the time domain from a parallel signal to a serial signal.

을 곱하여 정규화한다. The multiplier 157 multiplies the serial real signal

.

FIG. 10 is a diagram showing each modulation unit shown in FIG. 1, FIG. 11 is a diagram showing a phase size distribution of an input signal of each modulation unit, and FIG. 12 is a diagram showing a phase size distribution with respect to an output signal of each modulation unit.

Referring to FIG. 10, each modulator 160 includes a phase controller 161 and a modulator 163.

The phase controller 161 receives the real signal normalized from the real signal converter 150 as the input signal IN. The phase controller 161 adjusts the magnitude of the input signal IN by varying the gain G1 so that the magnitude of the input signal IN is in the range of -π / 2 to π / 2. Here, π is the circularity.

For example, when the phase of the input signal IN of the phase controller 161 is the same as that of FIG. 11, the phase controller 161 controls the phase of the input signal IN such that the magnitude of the input signal IN is in the range of -π / , The magnitude of the input signal IN can be adjusted by multiplying the input signal IN by a gain of 0.4. Then, as shown in Fig. 12, the phase magnitude of the input signal IN can be in the range of -π / 2 to? / 2.

The modulator 163 modulates the real signal adjusted by the phase controller 161 with the cosine signal and the sine signals cos (IN) and sin (IN).

13 is a view showing the PCPN shown in Fig.

Referring to FIG. 13, the PCPN 170 includes a PAPR controller 171 and multipliers 173 and 175. The multipliers 173 and 175 may operate as a power normalization unit for power normalization.

The cosine signal cos (IN), which is the output signal of the modulator 163, is represented by a (t) in FIG.

The cosine signal a (t), which is the output signal of the modulator 163, is input to the multiplier 173 without going through the PAPR controller 171 and the sine signal sin (IN), which is the output signal of the modulator 163, And is input to the PAPR controller 171.

The PAPR controller 171 controls the gain G2 in accordance with the input control signal and adjusts the magnitude of the sine signal sin (IN) input according to the gain G2. At this time, the control signal may include a gain value to be controlled.

That is, the PAPR controller 171 controls the PAPR by adjusting only the magnitude of the sine component of each modulated real signal. The sine signal [b (t)] adjusted by the PAPR controller 171 is input to the multiplier 175. [

Generally, the PAPR in one OFDM symbol is expressed by Equation (1). A guard interval is inserted into a time-domain serial signal output from the real signal converter 150, and a guard interval and a signal corresponding to one data symbol (or a pilot symbol) are combined to form an OFDM symbol.

[Equation 1]

Here, E {.} Denotes an expectation value, and T denotes a period of one OFDM symbol.

At this time, the PAPR (dB) according to the embodiment of the present invention can be expressed by Equation (2) and Equation (2).

&Quot; (2) "

&Quot; (3) "

In Equation (3), Gain represents the gain G2 of the PAPR controller 171, and when Gain is 1, PAPR becomes 0 dB.

In particular, as shown in Equation (3), the PAPR varies depending on the gain. That is, since the gain G2 can be controlled by the PAPR controller 171 using the control signal in accordance with the reception environment, the control of the PAPR can be also performed.

For example, the gain G1 of the phase controller 161 shown in FIG. 10 is 0.4, the size of the IFFT is 2048, and in the case of 16QAM modulation, the PAPR is calculated as the gain G2 of the PAPR controller 171 ). ≪ / RTI >

[Table 1]

The cosine signal a (t) and the scaled sine signal b (t) are then multiplied by the value of C for power normalization. C is expressed by Equation (4).

&Quot; (4) "

That is, the multiplier 173 multiplies the cosine signal a (t) by C to normalize the power, and the multiplier 175 multiplies the sine signal b (t) by C to perform power normalization.

A power normalized cosine signal LA baseband I signal, and when the power normalized sine signal LA baseband Q signal, the baseband I signal and each of the baseband Q signal cos (2πf _c t) and sin (2πf _c t) And then converted into a radio frequency signal.

FIG. 14 is a diagram illustrating an OFDM receiving apparatus according to an embodiment of the present invention, and FIG. 15 is a flowchart illustrating a data receiving method of an OFDM receiving apparatus according to an embodiment of the present invention.

14, the OFDM receiver 200 includes a reception signal processor 210, a power compensator 220, an Angle demodulation unit 230, a Real Signal De-Converter A pilot extractor 250, a channel estimator 260, a channel equalizer 270, a symbol demapper 280, and a PSC 290. The OFDM receiving apparatus 200 performs an inverse operation of the OFDM transmitting apparatus 100.

15, when the OFDM signal is received as reception data, the reception signal processing unit 210 multiplies the real component of the OFDM signal by A ', multiplies the imaginary component of the power normalized signal by B', and then performs analog-to-digital conversion Converts a passband analog signal into a plurality of baseband digital signals (S1502). Here, A 'and B' may be the same as A and B of the OFDM receiving apparatus 100, and B 'may be -B. A 'may be cos (2πf _c t) or sin (2πf _c t) and B' may be cos (2πf _c t) or sin (2πf _c t), which may be a different value from A '. f _c is radio frequency.

The power compensation unit 220 compensates the size adjusted by the PAPR controller 171 for a plurality of baseband digital signals (S1504).

Each demodulator 230 demodulates a plurality of baseband digital signals whose sizes are compensated by the power compensator 220 (S1506).

The real signal inverse transformer 240 transforms each demodulated signal from a serial signal to a parallel signal (S1508), and performs a fast Fourier transform (FFT) on the converted parallel signal to generate a parallel signal in the frequency domain Into a parallel symbol (S1510).

The pilot extracting unit 250 extracts pilot symbols from the frequency-domain parallel symbols (S1512).

The channel estimation unit 260 estimates a channel using the extracted pilot symbols (S1514).

The channel equalizer 270 compensates for the distortion caused by the channel using the channel estimated from the data symbol of each data symbol group (S1516).

The symbol demapping unit 280 demodulates the parallel data symbols in the frequency domain in which the distortion due to the channel is compensated by the channel equalizer 270 through symbol demapping through digital demodulation such as BPSK, QAM, 16-QAM, 64-QAM, To generate a plurality of parallel data signals (S1518).

The PSC 290 converts a plurality of parallel data signals output from the symbol demapping unit 280 into a plurality of serial data signals and outputs the serial data signals (S1520), thereby restoring the OFDM signals into data signals.

The OFDM receiving apparatus 200 will now be described in detail with reference to FIG. 16 to FIG.

16 is a diagram showing an example of a received signal processing unit shown in FIG.

16, the reception signal processing unit 210 includes multipliers 211 and 213, low pass filters (LPF) 215 and 217, an analog to digital converter (ADC) 219, .

The multiplier 211 multiplies the received OFDM signal by A 'to convert it into a cosine signal or a sine signal, and outputs it to the LPF 215. Was 16 in A 'is shown to be cos (2πf _c t), In this case, the signal output from the multiplier 211 may be an cosine.

The multiplier 213 multiplies the received OFDM signal by B ', converts it into a cosine signal or a sine signal, and outputs the result to the LPF 217. In FIG. 16, B 'is shown to be sin (2? F _c t), and the signal output from multiplier 211 may be a sine signal.

Here, A 'may be cos (2πf _c t) or sin (2πf _c t) and B' may be cos (2πf _c t) or sin (2πf _c t), which may be a different value from A '. The LPFs 215 and 217 filter the cosine signal and the sine input signal input from the multipliers 211 and 213, respectively, and pass only the signal of the desired band in the input signal.

The ADC 219 converts a cosine signal and a sine signal having passed through the LPFs 215 and 217 into a digital baseband I signal and a digital baseband Q signal through analog-to-digital conversion, Q signal.

On the other hand, it made signal [cos (2πf _c t) or sin (2πf _c t)] multiplied with the baseband Q signal from the OFDM transmission apparatus 100 (-), when multiplied by a code, ADC (219) is a digital baseband output The band Q signal can be multiplied by the negative sign.

17 is a diagram showing the power compensation unit shown in Fig.

Referring to FIG. 17, the power compensation unit 220 includes multipliers 221 and 223 and a PAPR controller 225.

The multiplier 221 multiplies the digital baseband I signal output from the reception signal processing unit 210 by D to compensate the power of the baseband I signal and outputs the multiplied signal.

The multiplier 223 multiplies the digital baseband Q signal output from the reception signal processing unit 210 by D, performs power compensation, and outputs the result to the PAPR controller 225.

Here, D can be expressed by Equation (5).

&Quot; (5) "

는 OFDM 송신 장치(100)에서의 코사인 신호[도 13의 a(t)]의 추정치를 나타내며,

는 OFDM 송신 장치(100)에서의 사인 신호[도 13의 sin(IN(t))]의 추정치를 나타낸다. 또한 Gain은 위상 제어기(도 10의 161)의 이득(G1)을 나타낸다. Here, T denotes a period of an OFDM symbol.

Represents an estimated value of the cosine signal (a (t) in FIG. 13) in the OFDM transmission apparatus 100,

Represents the estimated value of the sine signal (sin (IN (t) in FIG. 13) in the OFDM transmission apparatus 100. Gain represents the gain G1 of the phase controller (161 in Fig. 10).

및

는 IFFT된 신호가 랜덤 신호이므로 정확히 구할 수가 없다. 따라서, 여러 번 반복하여 평균함으로써 오차를 줄일 수 있고, OFDM 송신 장치(100)의 위상 제어기(도 10의 161)의 이득(G1)에 따른 추정치는 표 2와 같을 수 있다.

And

Can not be obtained exactly because the IFFT-processed signal is a random signal. Therefore, it is possible to reduce the error by repeatedly averaging several times, and the estimated value according to the gain G1 of the phase controller 161 (FIG. 10) of the OFDM transmission apparatus 100 can be as shown in Table 2. [

[Table 2]

The PAPR controller 225 divides the power compensated signal by the multiplier 221 by the gain G3 of the PAPR controller 223 and outputs the baseband Q signal. Is equal to the gain G2 of the PAPR controller 171 of the gain G3 of the PAPR controller 225. [ For example, if the gain G1 of the phase controller 141 (Fig. 10) is 0.4 and the gain G3 of the PAPR controller 225 is 2, then D becomes 1.179. Dividing the value obtained by multiplying the baseband Q signal by 1.179 by 2 produces a power compensated baseband Q signal.

FIG. 18 is a view showing each demodulating unit shown in FIG. 10, FIGS. 19 and 20 are views showing the phase estimating unit shown in FIG. 18, and FIG. 21 is a diagram showing the phase compensating unit shown in FIG.

18, the stabilizer 230 includes a phase estimator 231 and a phase compensator 233.

The phase estimator 231 performs phase estimation to compensate for phase distortion.

19, the phase estimating unit 231 includes an average calculating unit 2311 and a phase calculating unit 2313. [

)을 구한다. 예를 들어, IFFT의 크기가 N인 경우, 입력되는 기저대역 신호의 위상을 N개만큼 더한 후 N으로 나누면 평균(

)이 계산될 수 있다. The average calculation unit 2311 calculates an average of the input baseband signals (

). For example, if the size of the IFFT is N, the phase of the input baseband signal is added by N and then divided by N,

) Can be calculated.

)의 역탄젠트(arctan)를 이용하여 위상 추정값(

)을 계산한다.

는 수학식 6과 같이 평균(

)의 허수 성분을 평균(

)의 실수 성분으로 나눈 값의 역탄젠트를 통하여 계산될 수 있다. The phase calculator 2313 calculates the average (

) Using the inverse tangent (arctan)

).

As shown in Equation (6)

) ≪ / RTI >

) ≪ / RTI > divided by the real component < RTI ID = 0.0 >

&Quot; (6) "

)은 기저대역 신호의 평균(

)을 이용하여 구해질 수도 있지만 이와 다른 방법으로 구해질 수도 있다. Thus, the phase estimation value (

) Is the average of the baseband signal (

), But they can be obtained by other methods.

Referring to FIG. 20, the phase estimator 231 'may include an LPF 2311' and a phase calculator 2313 '.

)를 출력한다. The LPF 2311 'filters the input baseband signal to generate a low-band signal

).

)의 역탄젠트를 이용하여 위상 추정값(

)을 계산할 수 있다. The phase calculator 2313 'calculates the phase of the low-band signal (

) ≪ / RTI > is used to calculate the phase estimate < RTI ID =

) Can be calculated.

&Quot; (7) "

)을 이용하여 왜곡된 위상을 보상한다. Referring again to FIG. 18, the phase compensator 233 receives the phase estimation value (

) To compensate for the distorted phase.

21, the phase compensator 233 includes a phase calculator 2331, a controller 2333, an adder 2335, and a controller 2337. [

)을 구하고, 수학식 5 또는 6과 동일한 방법으로 위상(

)의 역탄젠트를 이용하여 위상 추정값(

)을 구한다. The phase calculator 2331 calculates the phase of the input baseband signal

) Is obtained, and the phase (

) ≪ / RTI > is used to calculate the phase estimate < RTI ID =

).

)을 입력 받아, -1을 곱하여 출력한다. The controller 2333 receives the phase estimation value (" 1 ") from the phase estimator 231 or 231 '

), Multiplies it by -1, and outputs it.

)과 제어기(2333)의 출력 값을 덧셈한다. The adder 2335 multiplies the phase estimate < RTI ID = 0.0 >

And the output value of the controller 2333 are added.

)에서 위상 추정부(231 또는 231')로부터 위상 추정값(

)을 뺄셈하는 역할을 한다. That is, the controller 2333 and the adder 2335 receive the phase estimation value of the phase calculator 2331

) From the phase estimator 231 or 231 '

).

)에서 위상 추정부(231 또는 231')로부터 위상 추정값(

)을 뺀 값을 이득(G4)으로 나눔으로써, 왜곡이 보상된 위상(P)을 출력한다. 여기서, 이득(G4)은 위상 제어기(161)의 이득(G1)과 동일할 수 있다. The controller 2337 receives the phase estimate value (< RTI ID = 0.0 >

) From the phase estimator 231 or 231 '

) Is divided by the gain G4, thereby outputting the phase P in which the distortion is compensated. Here, the gain G4 may be the same as the gain G1 of the phase controller 161. [

22 is a diagram showing the real signal converter shown in Fig.

22, the real signal converter 240 includes a multiplier 241, an SPC 243, an FFT unit 245, and a signal processing unit 247.

을 곱하여 정규화한 후에 SPC(243)로 출력한다. The multiplier 241 multiplies the real signal P output from each demodulator 230

And outputs it to the SPC 243 after normalization.

The SPC 243 converts the normalized signal from the serial signal into a parallel signal by the multiplier 241 to FFT the normalized signal, and outputs the parallel signal to the FFT unit 245.

The parallel signals converted by the SPC 253 are input to the input signals P (0), P (1), ..., , P (N-1), P (N), P (N + 1), ... , P (2N-1)], the FFT unit 245 outputs the input signals P (0), P (1), ... , P (N-1), P (N), P (N + 1), ... , P (2N-1)]. Then, the input signals P (0), P (1), ... , P (N-1), P (N), P (N + 1), ... , P (2N-1)] frequency domain data symbols [X (0), X (1), ... , X (N-1), X (N), X (N + 1), ... , X (2N-1)].

The signal processing unit 247 receives the frequency domain data symbols [(X (0), X (1), ..., X (N-1), X (N), X (N + (X (0), X (1), ..., X (N-1)) among the frequency domain signals The signal processing unit 247 may directly output the symbol [(X (0), X (1), ..., X (N-1)) to the pilot extracting unit 250. [ (2N-1), ..., X (2N-1)] and then relocates the data symbols to the position of X (2N-k) and outputs the relocated data symbols to the pilot extracting unit 250 For example, in the case of the symbol [X (2N-1)] in the frequency domain after FFT, the signal processing unit 247 calculates the frequency The symbol [X (2N-1)] of the region can be rearranged to the position of X (1) after the complex conjugate transformation.

23 is a diagram showing a pilot extraction method of the pilot extraction unit shown in FIG.

23, the pilot extracting unit 250 extracts, from the plurality of data symbols input in parallel, the position information of the symbol obtained by adding and subtracting the pilot symbols and the data symbols set by the OFDM transmitting apparatus 100 for each data symbol group (S2310).

The pilot extracting unit 250 extracts two symbols from each data symbol group from the position information of each data symbol group (S2320).

The pilot extracting unit 250 extracts the pilot symbols and one data symbol selected by the OFDM transmitting apparatus 100 using the extracted two symbols (S2330).

이고 파일럿 심볼에서 데이터 심볼을 뺀 심볼은

인 2개의 심볼이 수신되었다고 가정한다. 여기서,

는 정규화를 위해 사용된 것이다. 2개의 심볼을 더하고

로 나누면 1이 되고, 2개의 심볼을 빼고

로 나누면 3+j*5가 된다. When the OFDM transmission apparatus 100 adds and subtracts a pilot symbol and a selected data symbol to generate two new symbols, the two symbols obtained are added to become pilot symbols. If a difference between symbols obtained by adding two symbols and symbols obtained by subtracting two symbols is obtained, the data symbols are selected by the OFDM transmission apparatus 100. For example, when the pilot symbol is 1 and the data symbol selected by the OFDM transmitting apparatus 100 is 3 + j * 5, the symbol and data symbol are added to the symbol

And the symbol obtained by subtracting the data symbol from the pilot symbol is

≪ / RTI > is received. here,

Is used for normalization. Add two symbols

Divide by 1, and subtract two symbols

Divided by 3 + j * 5.

이고, 선택된 데이터 심볼에서 파일럿 심볼을 뺀 심볼은

인 2개의 심볼이 수신되었다고 가정한다. 2개의 심볼을 더하고

로 나누면 3+j*5가 되고 2개의 심볼을 빼고

로 나누면 1이 된다. When two new symbols are generated by adding and subtracting selected data symbols and pilot symbols from the OFDM transmission apparatus 100, two symbols are added to the selected data symbols. Then, the difference between the symbol obtained by adding the two symbols and the symbol obtained by subtracting the two symbols becomes a pilot symbol. For example, if the selected data symbol is 3 + j * 5 and the pilot symbol is 1, the symbol to which the pilot symbol is added to the selected data symbol is

, And the symbol obtained by subtracting the pilot symbol from the selected data symbol is

≪ / RTI > is received. Add two symbols

Divide by 3 + j * 5 and subtract 2 symbols

Is divided by 1.

The pilot extracting unit 250 arranges the extracted pilot symbols and the data symbols at a position located in the OFDM transmitting apparatus 100 (S2340).

FIG. 24 is a diagram illustrating a channel estimator shown in FIG. 14. FIG.

Referring to FIG. 24, the channel estimation unit 260 includes a multiplier 261, an LPF 263, and a divider 265.

The multiplier 261 multiplies the pilot symbol extracted by the pilot extracting unit 250 by the PN code generated by the OFDM transmitting apparatus 100 and outputs the result to the LPF 263. [

The LPF 263 filters the pilot symbols multiplied by the PN code to remove noise.

The divider 265 divides the data symbols of each data symbol group into pilot symbols of the corresponding data symbol group to estimate the channel. For example, if each pilot symbol of each data symbol group and each data symbol group is as shown in FIG. 7, each of the three data symbols of the first data symbol group is divided into a first pilot symbol, and seven of the second data symbol group Each of the data symbols may be divided by a second pilot symbol.

The symbol demapping unit 280 compensates for channel distortion by performing channel equalization using the channel estimated by the channel equalization unit 270 and compensates for the channel distortion corresponding to the symbol mapping unit 120 of the OFDM transmission apparatus 100 Demultiplexes each data symbol into a plurality of parallel data signals in a constellation according to the demodulation scheme, and outputs a plurality of parallel data signals to the PSC 280. Then, the PSC 280 converts the plurality of parallel data signals into a plurality of serial data signals to restore the data.

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (20)

In the apparatus for transmitting data,
A pilot generating unit for generating at least one pilot signal to be used for channel estimation in the data receiving apparatus,
A symbol mapping unit for mapping a plurality of data signals and the at least one pilot signal to generate a plurality of data symbols and at least one pilot symbol,
A real signal converting unit for converting an input symbol in a frequency domain including the plurality of data symbols and the at least one pilot symbol into a real signal in a time domain,
A modulation unit for modulating the real signal,
A PAPR control and power normalization unit adjusting the magnitude of the sine component of each modulated real signal according to the first gain and varying the first gain according to an input signal,
A signal transmitter for converting the size-adjusted real signal into a radio frequency signal and transmitting the radio frequency signal;
Lt; / RTI >
Wherein each modulator comprises:
A phase controller for controlling the magnitude of the real signal according to a second gain, and
And a modulator for modulating the real signal with a cosine signal and a sine signal,
Data transmission device. The method of claim 1,
A pilot symbol is set corresponding to each of a plurality of data symbol groups each including at least one data symbol, two symbols are generated using one data symbol and a pilot symbol of each data symbol group, Symbol groups and outputting them to the real signal converting unit,
Further comprising: 3. The method of claim 2,
The symbol arranging unit may combine the one data symbol and the pilot symbol to generate one symbol of the two symbols, subtract the one data symbol and the pilot symbol, and generate the other one of the two symbols Transmitting apparatus. delete The method of claim 1,
Wherein the real-
A normalizer for normalizing the input symbol so that an average power of the input symbol is 1,
An inverse fast Fourier transform unit for performing inverse fast Fourier transform on a plurality of input signals, and
An input signal processor for inputting a conjugate complex symbol obtained by performing conjugate complex conversion between the input symbol and the input symbol to the inverse fast Fourier transformer,
And a data transmission device. The method of claim 5,
Wherein the input signal processing unit comprises:
If the number of symbols of the input symbol is N, N data symbols are placed at positions of 0th to (N-1) th input signals, and the plurality of conjugate complex symbols are located at positions of (2N- However,
(2N-k) th input signal at the position of the input signal from (N + 1) th to (2N-1)
Wherein N is a positive number, and k is a value from N + 1 to 2N-1. The method of claim 1,
Wherein the PAPR control and power normalization unit comprises:
A PAPR controller for controlling a magnitude of a sine component of each modulated real signal according to the first gain,
A first multiplier for multiplying the cosine component of the real signal by a set value for normalization to generate a baseband I signal,
And a second multiplier for multiplying a sine component of the real signal whose magnitude is controlled according to the first gain by the set value to generate a baseband Q signal,
And the PAPR is 0 when the first gain is 1. In an apparatus for receiving data,
A power compensator for compensating for the magnitude of the baseband signal corresponding to the received data according to the size adjusted by the data transmitter for PAPR control,
And a demodulator for demodulating the size-compensated baseband signal,
A normalization and real signal inverse transformer for transforming each demodulated signal into a plurality of parallel symbols in a frequency domain in a time domain through fast Fourier transform,
A pilot extracting unit for extracting pilot symbols and data symbols from the parallel symbols,
A channel estimator for estimating a channel using the pilot symbol,
A channel equalizer for compensating the channel using the estimated channel, and
A symbol demapping unit for demapping the data symbols to generate a plurality of data signals to recover data,
Lt; / RTI >
Wherein each of the demodulators comprises:
A phase estimator for calculating a phase estimate value of the baseband signal, and
And a phase compensator for compensating the phase of the baseband signal from the phase estimate,
Wherein the power compensating unit comprises:
Two multipliers for respectively compensating the magnitudes of the I signal and the Q signal of the baseband signal, and
And a PAPR controller for outputting the Q signal having the magnitude compensated by dividing it by a gain,
The gain is variable
Data receiving apparatus. delete 9. The method of claim 8,
Wherein the phase estimator calculates an average value of phases of the baseband signal and calculates the phase estimate value using an inverse tangent of the average value. 9. The method of claim 8,
Wherein the phase estimator calculates the phase estimation value using an inverse tangent after filtering the baseband signal. 9. The method of claim 8,
The pilot extracting unit may extract positional information of two symbols generated from the parallel symbols using the pilot symbols in the data transmission apparatus, extract pilot symbols and data symbols using the two symbols corresponding to the positional information, Device. delete 9. The method of claim 8,
Wherein the real-
A fast Fourier transform unit for performing fast Fourier transform on a plurality of input signals to generate the parallel symbols,
A serial-to-parallel converter for converting the demodulated baseband signals from a serial signal to a parallel signal, and
And a signal processing unit for outputting a part of the parallel symbols to the demapping unit. In a method of transmitting data by a data transmitting apparatus,
Generating a plurality of pilot signals to be used for channel estimation in a data receiving apparatus,
Generating a plurality of data symbols and a plurality of pilot symbols by symbol-mapping a plurality of input signals and the plurality of pilot signals;
Converting an input symbol in a frequency domain including the plurality of data symbols and the plurality of pilot symbols from a frequency domain to a real signal in a time domain,
Modulating each of the real signals,
Controlling the magnitude of the sine signal for each modulated real signal according to the gain, and
Converting each of the modulated real-valued signals into a radio frequency signal and transmitting
Lt; / RTI >
Wherein each modulating step comprises:
Controlling the magnitude of the real signal according to a second gain, and
Modulating the real signal with a cosine signal and a sine signal
Gt; 16. The method of claim 15,
Wherein the generating comprises:
Setting a pilot symbol corresponding to each of a plurality of data symbol groups each including at least one data symbol,
Generating two symbols using one data symbol and pilot symbol of each data symbol group, and
And placing the two symbols in each data symbol group. 16. The method of claim 15,
Wherein the controlling comprises:
And varying the gain according to an input control signal. In the method by which the data receiving apparatus receives the data,
Compensating the size of the baseband signal corresponding to the received data,
Demodulating the baseband signal;
Transforming each demodulated signal into a plurality of parallel symbols in a frequency domain in a time domain through fast Fourier transform,
Extracting pilot symbols and data symbols from the parallel symbols,
Compensating a channel estimated using the pilot symbol, and
Demapping the data symbols to recover the received data;
Lt; / RTI >
Wherein each of the demodulating steps comprises:
Estimating the phase of the baseband signal, and
Compensating a phase of the baseband signal using a phase estimate;
The step of compensating for the magnitude of the baseband signal comprises:
Compensating a magnitude of an I signal and a Q signal of the baseband signal, respectively; And
Dividing the Q signal of the size compensated by the gain and outputting
Lt; / RTI >
Wherein the gain is variable. delete The method of claim 18,
Wherein the extracting comprises:
Acquiring position information of two symbols generated by using a pilot symbol in a data transmitting apparatus, and
And extracting pilot symbols and data symbols using two symbols corresponding to the position information.

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